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A236249 Primes of the form C(2*m, m) - prime(m), where C(2*m, m) = (2*m)!/(m!)^2. 5
3, 241, 911, 184727, 30067266499540931, 1454272161238683681127450712107767894181359647011258114106151524833563647084221 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Though the primes in this sequence are very rare, according to the conjecture in A236256 there should be infinitely many such primes.

See A236248 for a list of known numbers m with C(2*m, m) - prime(m) prime.

See also A236245 for a similar sequence.

LINKS

Zhi-Wei Sun, Table of n, a(n) for n = 1..12

EXAMPLE

a(1) = 3 since C(2*1, 1) - prime(1) = 0 is not prime, but C(2*2, 2) - prime(2) = 6 - 3 = 3 is prime.

MATHEMATICA

t[n_]:=Binomial[2n, n]-Prime[n]

a[n_]:=t[A234248(n)]

Table[a[n], {n, 1, 6}]

CROSSREFS

Cf. A000040, A000984, A236241, A236242, A236245, A236248, A236256.

Sequence in context: A264549 A024044 A069640 * A013778 A146313 A092799

Adjacent sequences:  A236246 A236247 A236248 * A236250 A236251 A236252

KEYWORD

nonn

AUTHOR

Zhi-Wei Sun, Jan 21 2014

STATUS

approved

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Last modified October 17 16:18 EDT 2018. Contains 316285 sequences. (Running on oeis4.)